Evolution and dissemination of mobile colistin resistance genes: limitations and challenges in Latin American countries
Authors: William Calero-Cáceres, José Luis Balcázar
Journal: The Lancet Microbe (2023)

The Article by Muhammad Umair and colleagues1Umair M Hassan B Farzana R et al.International manufacturing and trade in colistin, its implications in colistin resistance and One Health global policies: a microbiological, economic, and anthropological study.Lancet Microbe. 2023; 4: e264-e276Summary Full Text Full Text PDF PubMed Scopus (12) Google Scholar in The Lancet Microbe describes the usage of colistin in animals that are used for food and its effect on the emergence of colistin-resistant Enterobacterales, which are a global public health concern. The study found that colistin is still widely used in animals for treatment, metaphylaxis, prophylaxis, and growth promotion, despite its listing as a WHO Critically Important Antimicrobial for Human Medicine.1Umair M Hassan B Farzana R et al.International manufacturing and trade in colistin, its implications in colistin resistance and One Health global policies: a microbiological, economic, and anthropological study.Lancet Microbe. 2023; 4: e264-e276Summary Full Text Full Text PDF PubMed Scopus (12) Google Scholar The study also found a 7% (75 of 1131) prevalence of mcr-1-mediated colistin resistance in Escherichia coli in samples collected from various sources in Pakistan. The study calls for robust national and international laws to mitigate the international trade of colistin and improved surveillance and control measures to prevent the spread of antibiotic-resistant bacteria. Although colistin is not approved as a feed additive in Europe, Canada, or the USA, it is widely used as a feed additive in low-income and middle-income countries. In Latin American countries, where data on the use of polymyxin-based products for clinical and veterinary purposes and the identification of polymyxin-resistant Enterobacterales are scarce, several questions arise that hinder a comprehensive understanding of the evolution and dissemination of polymyxin-resistant Enterobacterales in this region. According to the supplementary data of this article, during 2018–21, Bolivia, Chile, Colombia, Ecuador, Mexico, Panama, Paraguay, Peru, and Venezuela acquired polymyxin derivatives from China and India, mainly for veterinary purposes, representing a considerable market for this family of antibiotics. However, for most Latin American countries, available information on the prevalence of polymyxin-resistant strains is scarce, and studies of the isolates are mainly focused on academic efforts instead of public health surveillance. According to the National Database of Antibiotic Resistant Organisms as of March 7, 2023, only six variants of mcr genes have been detected in Latin American countries, and the availability of whole-genome sequences is still limited in comparison with China, USA, and European countries. 329 (3·6%) of 9067 mcr-1 sequences were detected in Argentina, Bolivia, Brazil, Colombia, Ecuador, Dominican Republic, Mexico, Peru, and Venezuela (in Enterobacterales); 52 (4·5%) of 1168 of mcr-3 sequences were detected in Brazil, Chile, Colombia, Costa Rica, Mexico, and Peru (in Aeromonas spp); 33 (25·6%) of 129 mcr-5 sequences were detected in Brazil and Paraguay (in Enterobacterales); 62 (1·1%) of 5806 mcr-9 sequences were detected in Argentina, Brazil, Chile, Colombia, Ecuador, and Mexico (in Enterobacterales); and one (0·2%) of 438 mcr-10 sequences was detected in Brazil (in Enterobacter kobei).2NIHNational Database of Antibiotic Resistant Organisms (NDARO).https://www.ncbi.nlm.nih.gov/pathogens/antimicrobial-resistance/Date accessed: May 7, 2023Google Scholar Several factors such as geographical location, livestock farming methods, colistin usage, and antibiotic selective pressure can influence the selection and diversity of mcr gene variants.3Ling Z Yin W Shen Z Wang Y Shen J Walsh TR Epidemiology of mobile colistin resistance genes mcr-1 to mcr-9.J Antimicrob Chemother. 2020; 75: 3087-3095Crossref PubMed Scopus (149) Google Scholar However, given that these studies are mainly conducted by specific projects of local universities, there is a considerable gap in our understanding of the evolution and dissemination of mcr variants in Latin American countries. Consequently, these results only represent a small part of a larger picture. Latin American countries face several challenges in tracking the evolution and dissemination of colistin resistance. First, the difficulties of the standardisation of methods for polymyxin susceptibility can lead to inconsistent and incomplete data.4Ezadi F Ardebili A Mirnejad R Antimicrobial susceptibility testing for polymyxins: challenges, issues, and recommendations.J Clin Microbiol. 2019; 57: e01390-e01398Crossref PubMed Scopus (87) Google Scholar Second, limited access to advanced technologies such as whole-genome sequencing, which are necessary for identifying phylogenetic relationships, is often restricted to specific universities in the region.5Calero-Cáceres W Ortuño-Gutiérrez N Sunyoto T et al.Whole-genome sequencing for surveillance of antimicrobial resistance in Ecuador: present and future implications.Rev Panam Salud Publica. 2023; 47: e8Crossref PubMed Scopus (2) Google Scholar Third, in many low-income and middle-income countries, the scarcity of cross-sectoral collaboration among public health institutions has hindered the establishment of effective surveillance strategies to assess the evolution and dissemination of antimicrobial resistance.6Iskandar K Molinier L Hallit S et al.Surveillance of antimicrobial resistance in low- and middle-income countries: a scattered picture.Antimicrob Resist Infect Control. 2021; 10: 63Crossref PubMed Scopus (121) Google Scholar Considering this evidence, it is clear that Latin American countries face several challenges for antimicrobial resistance surveillance. In this context, there is a pressing need for a more active role of world health institutions to guide the adoption of proper public health strategies for the surveillance of antimicrobial resistance in Latin American countries. By providing technical assistance, capacity building, and access to resources and technology, these institutions could play a pivotal role in strengthening the capacity of local health authorities to monitor and control the spread of antibiotic-resistant bacteria, because around 84 000 deaths per year are directly attributable to antibiotic resistance in Latin American and Caribbean countries.7Murray CJL Ikuta KS Sharara F et al.Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis.Lancet. 2022; 399: 629-655Summary Full Text Full Text PDF PubMed Scopus (4398) Google Scholar We declare no competing interests. WC-C would like to thank the Operative Unit of the Directorate of Research, Department of Food and Biotechnology Science and Engineering at the Universidad Técnica de Ambato for providing their research facilities. JLB acknowledges the funding provided by the Generalitat de Catalunya through the Consolidated Research Group grant ICRA-ENV 2021 SGR 01282 and the funding from the CERCA program of the Catalan Government.